Bunina bodies in amyotrophic lateral sclerosis on Guam: a histochemical, immunohistochemical and ultrastructural investigation.

An investigation of Bunina bodies is important when studying the pathoetiology and pathomechanisms involved in amyotrophic lateral sclerosis (ALS). It may serve as a clue essential for the study of the pathogenesis of Guamanian amyotrophic lateral sclerosis (ALS-G), and it may provide a means of answering the question of whether ALS-G is the same disease as classical ALS or a different entity. In ALS-G, however, no precise histochemical, immunohistochemical, or detailed ultrastructural examination has been published to date. To elucidate the pathological differences/similarities of Bunina bodies between classical ALS and ALS-G, we performed histochemical, immunohistochemical, topographic and ultrastructural examinations. Histochemically, hematoxylin and eosin, Masson's trichrome, methylgreen-pyronin, phosphotungstic acid-hematoxylin, Klüver-Barrera, Bodian and periodic acid-Schiff staining were utilized. Immunohistochemical examination was performed using antibodies for cystatin C, ubiquitin, Tau-2, Cu/Zn superoxide dismutase, phosphorylated neurofilament and glial fibrillary acidic protein. Histochemical findings were consistent with those previously described for classical ALS. The immunohistochemical study showed that in ALS-G Bunina bodies were intensely labeled by an anti-cystatin C antibody. Topographic examination demonstrated that Bunina bodies were distributed in the spinal anterior horns and Clarke's column in the spinal cord. Ultrastructurally, Bunina bodies were composed of electron-dense amorphous/ granular material accompanied by vesicular structures and neurofilaments. The results of the present study have revealed that the pathological features of Bunina bodies in ALS-G are identical to those seen in classical ALS. These findings strongly suggest that a similar degenerative process occurs in the spinal anterior horn cells in both ALS-G and classical ALS.